3D printing with pellets and smart monitoring of the printing process

Sammanfattning: Additive manufacturing (AM) is a set of different techniques which use layer by layer deposition principle to join material together and manufacture three-dimensional objects from a CAD file. One of the most known and popular techniques within AM is Fused Deposition Modeling (FDM). Generally, the FDM process starts with a feedstock of filament which is pushed through an extruder head, which liquefies the filament and deposits it down on the print bed according to a specific pattern specified by the CAD file. This technique has found great success within the industry and has been adopted by many companies across many different applications such as automotive, aerospace and medical for rapid prototyping. The disadvantage with filaments is that the diameter tolerances are quite small which makes it expensive and difficult to manufacture. Another problem with 3D printing is the waste of money and time due to failed prints, both in the industry but also with private users. This is a result of not having a monitoring system that overwatches the printing process and stops the print when it detects defects, as the user usually does not stand by the printer and watch the whole process. The main aim of this study is to modify a desktop 3D printer to suit and install a pellet extruder and to investigate the feasibility of process monitoring for desktop printers. To evaluate the printability of the pellet extruder, tensile test artifacts are printed with PLA 4043D and TPE_S16300C in two different raster orientations and three different layer thicknesses, further, the influence of raster orientation and layer thickness on ultimate tensile strength is evaluated. Raster orientation refers to the different directions of the individual bead paths within a layer and layer thickness refers to the height of each layer that is deposited along the Z-axis. In this study, the pellet extruder was successfully installed on the Sovol SV01 printer. The open-source process monitoring system called the spaghetti detective was used during the experiments to monitor the 3D printing process. It uses a failure detection system (AI) to detect defects and automatically stop a print if defects are detected and alert the user via email or text. The tensile test artifacts were only printed with TPE_SE16300C and due to limitations in the pellet extruder, it is observed that tensile test samples were difficult to 3D print with PLA4043D. Regardless of the layer thickness, the 45°/-45° raster orientation produced a slightly higher ultimate tensile strength than the 0°/90° raster orientation. As for the influence of layer thickness on ultimate tensile strength, the increase of layer thickness in the 0°/90° raster orientation led to a decrease in ultimate tensile strength. In the 45°/-45° raster orientation no clear conclusion could be made as the differences were insignificant.